MongoDB.Driver 管道 Aggregate

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目前mongodb for C#这个驱动，在进行Aggregate时，只支持BsonDocument类型，也就是说，你的集合collection也必须返回的是BsonDocument，而实体类型是不可以被认出的，这点要注意．

public IAsyncCursor<BsonDocument> GetAggregate(MongodbHost host,PipelineDefinition<BsonDocument, BsonDocument> pipeline)
{
MongoClient client = new MongoClient(host.Connection);
var dataBase = client.GetDatabase(host.DataBase);
var dataTb=dataBase.GetCollection<BsonDocument>(host.Table);
return dataTb.Aggregate(pipeline);
}

public class MongodbHost
{
/// <summary>
/// 连接字符串
/// </summary>
public string Connection { get; set; }
/// <summary>
/// 库
/// </summary>
public string DataBase { get; set; }
/// <summary>
/// 表
/// </summary>
public string Table { get; set; } }

MongodbHost mongodbHost = new MongodbHost();
mongodbHost.Connection = "mongodb://test1:test1@127.0.0.1:27017/mytest";
mongodbHost.DataBase = "mytest";
mongodbHost.Table = "testtb1"; const string pipelineJson1 = "{$group:{_id:'$Symbol',Value:{$max:'$Value'}}}";//" {$project : {DTime : 1 ,AdvInf : 1}}";
const string pipelineJson2 = " { $match : { AdvInf : { $eq :3 } } }";
const string pipelineJson3 = " { $match : { DTime : { $gte :ISODate('2018-12-04T02:20:12') } } }"; IList<IPipelineStageDefinition> stages = new List<IPipelineStageDefinition>();
PipelineStageDefinition<BsonDocument, BsonDocument> stage1 =
new JsonPipelineStageDefinition<BsonDocument, BsonDocument>(pipelineJson1);
PipelineStageDefinition<BsonDocument, BsonDocument> stage2 =
new JsonPipelineStageDefinition<BsonDocument, BsonDocument>(pipelineJson2);
PipelineStageDefinition<BsonDocument, BsonDocument> stage3 =
new JsonPipelineStageDefinition<BsonDocument, BsonDocument>(pipelineJson3); stages.Add(stage1);
//stages.Add(stage2);
//stages.Add(stage3); PipelineDefinition<BsonDocument, BsonDocument> pipeline = new PipelineStagePipelineDefinition<BsonDocument, BsonDocument>(stages); var gdValue = GetAggregate(mongodbHost,pipeline);